This project will enhance risk assessment and control strategies for the
increasing possibility of environmental contamination by antibiotic-resistant
bacteria, which could transfer their resistance genes to human pathogens in
the environment or via harmless indigenous microorganisms ingested by humans.
Gene transfer could occur by direct mechanisms such as conjugation (i.e.,
cell to cell mating with plasmid or chromosomal gene transfer), or by indirect
processes such as transformation (i.e., cell uptake of free DNA from the environment),
and transduction (i.e., transfer via virus) (Madigan et al., 2000). Note that
gene vectors may soon become an important category of pollutants that may
experience a different fate than the bacteria that initially harbor them,
due to horizontal and vertical gene transfer. Thus, determining the fate,
transport, transfer, and decay kinetics of gene vectors in the environment
will help formulate more accurate mathematical models to support regulatory
and management decisions (e.g., to set total maximum daily loads [TMDLs]).
This project will also train graduate students and hence, it will not only
benefit environmental and public health, but it will also strengthen our scientific,
engineering, research, education, and human resource base. At the conclusion
of this study, the environmental factors and mechanisms affecting the persistence
of antibiotic resistance genes will be better understood and our capability
to assess and manage the associated risks will be improved.